Growth of highly oriented epitaxial thin films has received increased interest due to their magnetic and transport properties. Such oriented films can enhance specific properties such as magnetic anisotropy that are dependent upon crystallographic direction. For example, an L10 FePt film used as a perpendicular magnetic recording medium requires a (001) texture such that the easy axis of magnetization lies orthogonal to the film plane. As another example, a thin film of lead zirconium titanate (PZT) may be c-axis oriented between top and bottom electrodes in a ferroelectric capacitor for optimal electrical properties.
There are numerous single crystal substrates such as GaAs, InAs, SrTiO3 and LaAlO3 that provide adequate lattice spacing and crystal structure for epitaxial growth of single crystal metals and oxides used in data storage and other applications. However, these substrates are quite expensive compared with basic silicon substrates, which limits their use considerably. A more economical approach would be to start with a relatively inexpensive substrate, such as silicon, and deposit metal or oxide films on the substrate with a well defined orientation and crystal structure that mimics a single crystal material.
Epitaxial ferroelectric thin films deposited on silicon wafers have potential for high density probe storage media. However, there are challenges in using epitaxial ferroelectric thin films for high-density probe recording media. Defects in the film should be minimized. In particular, grain boundaries and voids should be avoided because they act as channels for leakage current and increase the media noise. In addition, the polarization value should be maximized in order to achieve a higher read signal and thermal stability. Furthermore, surface roughness should be minimized in high-density recording applications. Surface morphology plays a major role in domain wall pinning and affects recording jitter and data density.